Catholic overnight (residential) summer camp for youth roughly ages 8-16, set on a 983-acre site in the Shawnee National Forest of southern Illinois. Campers stay in week-long sessions filled with horseback riding on wooded trails, rock climbing, swimming and paddling on three on-site lakes, and campfire traditions. Founded in 1959 and accredited by the American Camp Association, with an equestrian program accredited by the Certified Horsemanship Association.
The practical details
We list only what the camp itself publishes, and programs change — dates, prices, ages and availability can all move after we check. Confirm the details on the camp’s own website and contact Diocese of Belleville directly before you register or pay. Last checked August 2026.
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Accreditations & licensing
As stated by the camp or listed in the accrediting organization's directory — confirm current status with the accreditor.
Google Reviews
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★★★★★Cloud wilsonI went to Camp O' for the first time at the age of 10 (just over 20 years now.) I went for 3 summers(row Amantacha, row, row Amantacha!) , and I have to say it left one of the largest impressions on my life... I still tell friends about how great it was today. My God daughter is finally of age to go next year, and I plan on sending her with her parent's permission. I also can not wait for my son to be old enough to go; he's only 1 1/2, but he is definitely a shoe-in for mini camp! I absolutely cherish the memories I made at Camp, and I can't wait for the next generation to as well. P.s.: Slashies rule
★★★★★Russ JewellBeen visiting camp ondesonck for 50+ years. Hills and fields named after my late Uncle Morgan. It just feels like home. And the managers are very nice people. There is nowhere else that I feel this content
★★★★★Shawn WaltonGo when off season when no kids are in camp. Register at office. Sign waiver online. Go hike to Cedar Falls
★★★★★Dina HydeWe spent a wonderful 3 days in the Loretto unit of Fournie Lodge at Camp Ondessonk. We used our stay as a hub for hiking a number of Shawnee NF trails nearby. The unit has 2 bedrooms, bath and a large great room with gas fireplace. The kitchen is well appointed and there is an outdoor grill and fire pit. Beautiful touches throughout. Lovely views of the lake and amazing stargazing. It was a blessed time!
★★★★★Emily2025: My child return - still just as fun and so well-kept. Food is still awful with very limited options. Yogurt and salad bar were empty when they got to the cafeteria each day. 2023:Extremely well kept and clean camp, lots of activities for kids, and plenty of space. The only feedback would be the need for better food. Edit: Meals-- D1 - Sloppy Joes/sweet potatoes and meatloaf/baked potato. (no additional veggies or sides - ground beef for 2 meals) D2 - Breakfast was fine but lunch was just a plate of ham (no cheese or turkey) with chips and granola bars (no veggies or fruits).